1. Field of the Invention
The present invention relates to an oscillation apparatus, and more particularly, to a triangular-wave generating apparatus.
2. Description of the Related Art
A prior art triangular-wave generating apparatus is connected to an external capacitor for generating an output voltage (see: JP-2002-217687A). This prior art triangular-wave generating apparatus is constructed by a first constant current source for charging the external capacitor, a charging switch, a discharging switch, a second constant current source for discharging the external capacitor, a charging/discharging current setting circuit, a level determining circuit and a driver formed by an RS flip-flop.
The charging/discharging current setting circuit sets a charging current in the first constant current source and sets a discharging current in the second constant current source.
The level determining circuit is constructed by a first comparator for determining whether or not the output voltage reaches a high level to generate a first comparison signal, and a second comparator for determining whether or not the output voltage reaches a low level to generate a second comparison signal. The first and second comparison signals are supplied to the driver (RS flip-flop). That is, when the output voltage reaches the high level, the RS flip-flop is set to turn ON the discharging switch and turn OFF the charging switch, thus entering a discharging mode. On the other hand, when the output voltage reaches the low level, the RS flip-flop is reset to turn ON the charging switch and turn OFF the discharging switch, thus entering a charging mode.
This prior art triangular-wave generating apparatus will be explained later in detail.